1. Field of the Invention
The present invention generally relates to providing Internet Protocol (IP) telephony services to a collection of users behind aggregate endpoints that connect to a network, such as business customer sites or wholesale customer sites. Examples of IP telephony services include the EP Multimedia Subsystem (IMS), as well as other services in which user endpoints are required to register to the network in order to receive reliable service.
2. Brief Description of the Related Art
In the Internet Protocol (IP) Multimedia Subsystem (IMS) standard, which was originally designed for the individual subscriber wireless networks and is incorporated herein by reference, all subscribers need to register first before they can obtain services from the IMS network. As defined in the 3rd Generation Partnership Program (3GPP) IMS standard for, IMS network service providers use a Public User Identity (PUID) as the identifier to recognize the subscriber. The PUID is included in a P-Asserted-Identity (PAI) header in Session Initiation Protocol (SIP) INVITE messages for outbound calls, Request-URI header in SIP Invite messages for inbound calls, and the To header in SIP registration messages.
As service providers increasingly offer services to aggregate or collections of users or subscribers, such as business and wholesale customers, using the same IMS network that provides reliable services to individual subscribers, the following key issues arise:                1. Customer Premise Equipment (CPE) devices for business or wholesale customer equipment do not register with the (IMS) network. Examples of some endpoints that cannot register are:                    (a) legacy Time Division Multiplexing (TDM) Public Branch Exchanges (PBXs) that access an IP network through a Voice-Over-IP (VoIP) gateway;            (b) an IP device at customer premises that can not perform registration, such as IP PBX, or CPE running teleconferencing application; and in some cases, the PBX is a stateful proxy serving local IP phones, it usually is also their Registrar and thus will not forward the phone Registers on to the Core; and            (c) wholesale equipment access to the IMS network via routers.                        2. Business or wholesale services are applied to the connection or group instead of the individual subscriber. For example, based on a wholesale access point connection to the service provider, the wholesale service needs to be invoked as the originating service treatment for call screening, blocking, and routing.        